diff --git a/NEWS.md b/NEWS.md
index c5eee36033..7483099978 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,3 +1,7 @@
+### Unreleased
+
+* Added button to toggle Terrain Brush to full tile mode (by Finlay Pearson, #3407)
+
 ### Tiled 1.10.2 (4 August 2023)
 
 * Added support for setting custom properties on the project (#2903)
diff --git a/src/tiled/resources/images/scalable/fill-full-tiles.svg b/src/tiled/resources/images/scalable/fill-full-tiles.svg
new file mode 100644
index 0000000000..01dbb154c8
--- /dev/null
+++ b/src/tiled/resources/images/scalable/fill-full-tiles.svg
@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE svg  PUBLIC '-//W3C//DTD SVG 1.1//EN'  'http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd'>
+<svg enable-background="new 0 0 24 24" version="1.1" viewBox="0 0 24 24" xml:space="preserve" xmlns="http://www.w3.org/2000/svg">
+<g opacity=".55">
+	<rect x="4" y="4" width="16" height="16" fill="#214A88"/>
+	<rect x="5" y="5" width="4" height="4" fill="#719FCF"/>
+	<rect x="10" y="5" width="4" height="4" fill="#719FCF"/>
+	<rect x="15" y="5" width="4" height="4" fill="#719FCF"/>
+	<rect x="15" y="10" width="4" height="4" fill="#719FCF"/>
+	<rect x="15" y="15" width="4" height="4" fill="#719FCF"/>
+	<rect x="10" y="15" width="4" height="4" fill="#719FCF"/>
+	<rect x="5" y="15" width="4" height="4" fill="#719FCF"/>
+	<rect x="5" y="10" width="4" height="4" fill="#719FCF"/>
+	<rect x="6" y="6" width="2" height="2" fill="#507FB7"/>
+	<rect x="11" y="6" width="2" height="2" fill="#507FB7"/>
+	<rect x="16" y="6" width="2" height="2" fill="#507FB7"/>
+	<rect x="16" y="11" width="2" height="2" fill="#507FB7"/>
+	<rect x="16" y="16" width="2" height="2" fill="#507FB7"/>
+	<rect x="11" y="16" width="2" height="2" fill="#507FB7"/>
+	<rect x="6" y="16" width="2" height="2" fill="#507FB7"/>
+	<rect x="6" y="11" width="2" height="2" fill="#507FB7"/>
+</g>
+	<rect x="9" y="9" width="6" height="6" fill="#214A88"/>
+	<rect x="10" y="10" width="4" height="4" fill="#719FCF"/>
+	<rect x="11" y="11" width="2" height="2" fill="#3465A5"/>
+</svg>
diff --git a/src/tiled/wangbrush.cpp b/src/tiled/wangbrush.cpp
index 1c78151b4f..3c2e982112 100644
--- a/src/tiled/wangbrush.cpp
+++ b/src/tiled/wangbrush.cpp
@@ -31,6 +31,7 @@
 #include "mapscene.h"
 #include "painttilelayer.h"
 #include "tilelayer.h"
+#include "actionmanager.h"
 
 #include <QStyleOptionGraphicsItem>
 #include <QtMath>
@@ -88,6 +89,21 @@ WangBrush::WangBrush(QObject *parent)
                        new WangBrushItem,
                        parent)
 {
+    // Set up toolbar action for toggling fill full tiles mode,
+    // which basically makes the brush bigger.
+
+    QIcon fillFullTilesIcon(QLatin1String(":images/scalable/fill-full-tiles.svg"));
+
+    mToggleFillFullTiles = new QAction(this);
+    mToggleFillFullTiles->setCheckable(true);
+    mToggleFillFullTiles->setIcon(fillFullTilesIcon);
+    mToggleFillFullTiles->setText(tr("Fill Full Tiles"));
+
+    ActionManager::registerAction(mToggleFillFullTiles, "ToggleFillFullTiles");
+    connect(mToggleFillFullTiles, &QAction::toggled, this, [this](bool checked) {
+        mIsTileMode = checked;
+        stateChanged();
+    });
 }
 
 WangBrush::~WangBrush()
@@ -151,7 +167,8 @@ void WangBrush::mouseReleased(QGraphicsSceneMouseEvent *event)
 
 void WangBrush::modifiersChanged(Qt::KeyboardModifiers modifiers)
 {
-    const bool isTileMode = modifiers & Qt::ControlModifier;
+    const bool isControlPressed = modifiers & Qt::ControlModifier;
+    const bool isTileMode = isControlPressed != mToggleFillFullTiles->isChecked();
     const bool rotationalSymmetry = modifiers & Qt::AltModifier;
     const bool lineMode = modifiers & Qt::ShiftModifier;
 
@@ -179,6 +196,7 @@ void WangBrush::modifiersChanged(Qt::KeyboardModifiers modifiers)
 void WangBrush::languageChanged()
 {
     setName(tr("Terrain Brush"));
+    mToggleFillFullTiles->setText(tr("Fill Full Tiles"));
 }
 
 void WangBrush::setColor(int color)
@@ -670,6 +688,11 @@ void WangBrush::updateBrushAt(WangFiller &filler, QPoint pos)
     }
 }
 
+void WangBrush::populateToolBar(QToolBar *toolbar)
+{
+    toolbar->addAction(mToggleFillFullTiles);
+}
+
 } // namespace Tiled
 
 #include "moc_wangbrush.cpp"
diff --git a/src/tiled/wangbrush.h b/src/tiled/wangbrush.h
index db1b2347a1..252bcce56f 100644
--- a/src/tiled/wangbrush.h
+++ b/src/tiled/wangbrush.h
@@ -26,6 +26,8 @@
 #include "wangfiller.h"
 #include "wangset.h"
 
+#include <QToolBar>
+
 namespace Tiled {
 
 class WangBrushItem : public BrushItem
@@ -74,6 +76,8 @@ class WangBrush : public AbstractTileTool
 
     void setColor(int color);
 
+    void populateToolBar(QToolBar *toolbar) override;
+
 signals:
     void colorCaptured(int color);
 
@@ -120,6 +124,7 @@ public slots:
     bool mRotationalSymmetry = false;
     bool mLineStartSet = false;
     BrushBehavior mBrushBehavior = Free;
+    QAction *mToggleFillFullTiles;
 };
 
 } // namespace Tiled